Chain printer



July 4, 1961 F. M. DEMER ET AL CHAIN PRINTER 3 Sheets-Sheet 1 Filed Dec. 24, 1957 INVENTORS F. M. DEMER ET AL July 4, 1961 CHAIN PRINTER 3 Sheets-Sheet 2 Filed Dec. 24, 1957 INVENTORS FREDERICK M. DEMER RICHARD H. HARRINGTON ALEX ESHALKEY' Y THEIR ATTORNEYS July 4, 1961 F. M. DEMER ET AL CHAIN PRINTER Filed Dec 24, 1957 3 Sheets-Sheet 5 FIG.4.

PRINT CYCLE POINT HAMMER CLUTCH OPERATING TIME DETERMINATION-M TIME bll

l l l I l I l 1 l l L l I I l I THYRATRON PLATE VOLTAGE CLUTCH ROTOR VOLTAGE V V 0 o m V w M D D W GE E LG G T A ADA ART RL T L V O EO V H 0 T c INVENTORS FREDERICK M.DEMER RICHARD H. HARRINGTON ALEX T SHALKEY $4g a? THEIR ATTORNEYS 2,990,767 CHAIN PRINTER Frederick M. Demer, Johnson City, Richard H. Harrington, Vestal, and Alex T. Shalkey, Endicott, N. assignors to International Business Machines Corporation,

New York, N.Y., a corporation of New York Filed Dec. 24, 1957, Ser. No. 704,938

2 Claims. (Cl. 10193) This invention relates to printing mechanisms and more particularly to printers in which a plurality of hammer means are adapted to be actuated selectively to strike type characters mounted for movement in a continuous ath.

p Printers have been devised in which type members are arranged in a plurality of rows on frames moving continuously in one direction past the ends of hammers, means being provided for actuating the hammers so as to strike the type members for printing characters in lines on a record medium. While many designs of such printers are effective, usually the structure has been relatively complex because of the multiplicity of mechanical parts involved so that very high operating speeds can be achieved only at considerable expense.

It is an object of the invention, accordingly, to provide new and improved printer mechanism of the above char acter which is capable of high operating speeds Yet numbers relatively few mechanical parts and is relatively low in cost.

Another object of the invention is to provide new and improved printer mechanism of the above character which is adapted for use with high speed electronic control systems.

A further object of the invention is top-rovide new and improved printer mechanism of the above character in which characters are printed in a line on a record medium at high speed.

These and other objects of the invention are attained by mounting a plurality of type characters in a continuous pathv having a portion extending transversely of a record medium on'which characters are to be printed. Disposed in striking relation to the type characters in said path portion are a plurality of hammer means which are adapted to be actuated selectively to strike adjacent type characters. The hammers are adapted to be actuated selectively by electrostaticclutch means in response to electric signals. Also, means is provided for preventing actuation of any hammer means until all hammer means required to be activated to print a desired line of characters have been selected.

The invention may be better understood from the following detailed description of a typical embodiment, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of typical printer mechanism constructed according to the invention;

FIG. 2 is a partial rear view in perspective showing how the respective hammer means are coupled to the electrostatic clutch;

FIG. 3 illustrates one way of energizing the electrostatic clutch to actuate the type hammers selectively; and

FIG. 4 is 'a graph illustrating how a circuit of the type shown in FIG. 3 might be controlled to operate printing mechanism as in FIGS. 1 and 2.

Referring now to FIG. 1, a typical-printer mechanism according to the invention comprises an endless belt supported on spaced apart rollers 11 and 12 and having mounted thereon a plurality of type members 13 each of which carries a number of type characterson a plate 14 on one side thereof. On the other side of each type member 13 are formed a plurality of'teeth 15 equal in number to the type characters and having the same spacfnited States Patent ice ing therebetween. The teeth 15 are adapted to be sensed by a plurality of spaced apart magnetic pickup heads 16 and 17 to provide timing signals for use in the control of the machine. The belt also carries another magnetic member 19 which is adapted to be sensed by a magnetic pickup head 18 to provide a unique signal each time a predetermined type character on the belt is in the correct position to be struck by a predetermined one of the hammers described below.

The belt 10 is adapted to be driven by conventional motive means 20 through the gearing 21 and shaft 22. The type members 13 on the belt 10 are adapted to be moved transversely of a record strip 23 which passes under and'over guide members 24 and 25, respectively, and is adapted to be advanced intermittently in the usual manner by lower sprockets 26 and upper sprockets 27. To this end, the lower sprockets 26 are adapted to be driven by conventional motive means 28 and are also coupled in driving relation to the sprockets 27 by a belt 29 mounted on rollers 30 and 31 carried by shafts 32 and 33, respectively.

Printing of characters on the record strip 23 is adapted to be effected by a plurality of hammers 34 -34 respectively, rotatably mounted on a common shaft 35. The hammers 34 -34 respectively, are normally maintained away from the record strip 23 by spring means 36 -36 inclusive, as shown in FIGS. 1 and 2.

Interposed between the row of hammers 34 -34 and the record strip 23 is an inked ribbon 37 which is adapted to be advanced from a supply spool 38 and through a guide member 39 by a take-up spool 40 mounted on the shaft 32 which carries the roller 30.

The hammers 34 -34 are adapted to be actuated by an electrostatic clutch mechanism 41 comprising -a high resistance composition drum 42 having a dielectric lubricant such as silicone oil or the like on the peripheral surface thereof. The drum 42 is adapted to be driven continuously by motivepleans 43. Each of the hammers 34 34 has a lever arm 44 -44 to which is secured a narrow metal band 45 -45 which passes over the drum 42 and is retained by spring means 46 -46 secured to a member 46a.

When the mechanism is idle the metal bands 45 -45 are maintained out of engagement with the face of the drum 42 by a plurality of spacer members 47, 48 and 49 which are made of insulating material and are supported on the shaft 50 of the motor 43 for relative rotation with respect thereto. After rotation of the drum 42 is begun, the spacer members 47, 48 and 49 are removed so that all of the bands 45 -45 are in sliding engagement with the drum 42. Without the spacer members, the bands would stick to the drum when the drum was at rest and make it difficult to start the mechanism.

The spacer members 47 and 48 are provided with arcuate openings 51 and 52, respectively, through which is adapted to pass a rod 53 secured to the spacer member 49 and to a gear 54 also mounted on the shaft 50 for rotation with respect thereto. The gear 54 engages a toothed sector '55 which is pivotally mounted on a shaft 56 and is adapted to be rotated by a solenoid 57 through a linkage 58.

The printing mechanism shown in FIGS. 1 and 2 is adapted to be operated in conjunction with an electronic control system which forms no part of the invention, and, therefore, need not be described in detail herein. Suffice it to say that the control system is synchronized with the printer mechanism through the signals induced in the mag netic .pickup devices 1'6, 17 and .18 and during part of its cycle of operation is adapted to establish a potential difference between the drum 42 and any one of the metal bands 45 -45, corresponding to hammers that are required to be actuated.

This may be accomplished by a clutch control circuit of the type shown in FIG. 3, one of which is provided for each of the hammers 34 -34 in the machine of FIGS. 1 and 2. It comprises a conventional gas discharge tube 59, preferably a thyratron, having an anode 60, a. shield grid 61, a control grid 62 and a cathode 63. The anode 60 is connected by a unilaterally conductive device 64 and a conductor 65 to the band 45 Also, the band 45 is connected through a resistor 66 to a conductor 67 which supplies signal voltage to the drum 42.

The graphs shown in FIG. 4 illustrate a typical operating cycle for each of the control circuits of FIG. 3 in the printing machine of FIGS. 1 and 2. During the period (1+1) a voltage of say 200 volts is applied to the anode 60 of each of the thyratrons 59 through the resistor 68. During the period a a high shield grid voltage is also applied to the shield grids 61 of all the thyratrons. Any thyratrons that are to be fired also receive a signal at the control grid 62 and are thereby caused to become conducting. When this occurs, the voltage at the point A (FIG. 3) will drop from 200 volts to approximately 12 volts for all thyratrons fired. The voltage values of either 200 volts for unfired thyratrons or 12 volts for fired thyratrons at point A is isolated from the bands 45 -45 and from the rotor 42 by the back resistance of the unilaterally conductive device.

At the start of period b (FIG. 4) a voltage of 200 volts is applied to the conductor 67, raising to this potential the drum 42 and any of the bands 45 -45 whose control thyratrons have not been fired. Those of the bands 45 -45,, whose thyratrons have been fired, however, will be maintained at a potential of 12 volts by current passing through the resistor 66, the unilaterally conductive device 64 and the fired thyratron 59. The voltage difference between the drum 42 and those bands whose thyratrons have been fired, therefore, will be 188 volts, and those bands will be gripped by the drum to actuate the associated hammers.

Any band that has been energized and has a potential difference with respect to the drum 42 will now be drawn tightly against the drum 42 which in its rotation will apply tension to the corresponding metal band to actuate the corresponding hammer, and each hammer is actuated by a uniform force due to uniformity in frictional engagement of the respective bands. Upon the conclusion of the printing operation, the solenoid 57 is deenergized permitting the spring 59 to return the spacer members 47, 48 and 49 to their initial positions where they maintain the metal bands 45 -45,, in spaced relationship to the drum 42. The spacer members 47, 48 and 49 in moving between the metal bands 45 --45 and the drum operate to break the frictional engagement between the bands and the film of the drum.

In a practical mechanism, 120 hammers 34 -34,, may be disposed behind the record strip 23. The drum 42 of the electrostatic clutch 41 may be approximately 2 /2 inches in diameter and as wide as the print line. The drum speed may be approximately 800 to 900 rpm, the hammer firing time at this speed being between 500 and 600 microseconds.

The invention thus provides novel and highly effective printer mechanism for selectively actuating a plurality of hammer means to strike type characters mounted for movement in a continuous path. By employing electrostatic clutch means to actuate the several hammers as described above, the structure is relatively simple and inexpensive yet enables very high speeds of operation to be achieved.

It will be understood that the specific embodiment described above is susceptible of modification in form and detail within the skill of the art. The invention, therefore, is intended to cover all such modifications as come within the scope of the following claims.

We claim:

1. In printer mechanism the combination of a plurality of hammers disposed side by side in linear array and pivotally mounted for rotation about a common axis, resilient means normally maintaining said hammers in retracted position, a rotatable drum having an axis parallel to the axis of rotation of said hammers, and having a circumferential surface providing a condenser plate electrode and operably covered with a dielectric lubricant, means to continuously rotate said drum, a linear array of linkages of which each is connected at one end to a respective hammer and at the other end to a fixed point, and of which each has between its ends a portion wrapped around a portion of the circumference of said drum, a plurality of flexible electro-conductive metal bands of which each forms the wrapped portion of a respective one of said linkages, and of which each provides a condenser plate electrode closely spaced to said drum surface, whereby said surface, dielectric lubricant and each band form a separate condenser respective to that band, resilient means adapted by contracting said linkages to maintain the bands of said linkages in contact with said drum at a light pressure such that said bands normally slip freely over said rotating drum, a plurality of first terminals of which each is electrically connected to a respective one of said bands, a second terminal electrically coupled to said drum surface, and a plurality of voltage generating circuits of which each is connected between said second terminal and a respective one of said first terminals, each such circuit being selectively conditionable independently of the others between off and on conditions characterized by, respectively the absence and presence of a voltage applied from such circuit between the associated band and said drum surface of a value sufiicient to cause a gripping through dielectric force of such band by said surface and, thereby, an actuation of the associated hammer.

2. In printer mechanism, the combination of a rotatable drum, a plurality of hammers each registering with a separate axial portion of said drum and spaced from said drum to form a linear array, a plurality of resilient linkages of which each is connected at one end to a respective hammer and at the other end to a fixed point, and of which each between its ends has a portion wrapped around said drum over a portion of the circumference thereof defining an arc of predetermined extent about which all said linkages extend, at least one spacer member extending axially of said drum and angularly positioned within said are portion and underneath said linkage portions between such portions and said drum when said drum is stationary, said spacer member being adapted to lift said linkage portions from the surface of said drum prior to rotation thereof, a mounting for said member which renders the same rotatable about the axis of said drum to permit selective angular adjustment thereof from said position within said are to a position outside said arc which allows said linkage portions to bear on said surface of said drum to precondition said linkage portions for effective operation when the same is rotating, and, also, from said last named position back to said first named position to relift said linkage portions from the surface of said drum when the same is again stationary, means to continuously rotate said drum when said member is at said position without said are, and means to render selected ones of said linkages when so pro-conditioned to be driven by said rotating drum so as to actuate the hammer connected to each of said ones of said linkages.

References Cited in the file of this patent UNITED STATES PATENTS 2,686,470 Gore Aug. 17, 1954 2,766,686 Formenko Oct. 16, 1956 2,831,424 MacDonald Apr. 22, 1958 

